Recent developments have been made wherein glass batch is reduced to a molten state and refined in a furnace and the molten glass flows through forehearth channel to stream feeders or bushings disposed along the forehearth and the streams of the glass delivered through orifices in the feeders or bushings and attenuated into filaments by winding a strand of the filaments upon a rotating collector. This latter process is referred to as a direct melt process in the melting and refining of the glass by the application of heat, the temperature of the molten glass is brought to a temperature that is comparatively high in order to effect refining of the glass. During this process of melting and refining of glass, gases and volatiles are emitted or driven off from the melt. This action of melting and refining the glass at elevated temperatures renders the glass substantially stable for any temperature less than the minimum melt temperature in the furnace. Heretofore in the direct melt process, the temperatures of the glass in the forehearth channel and the stream feeders or bushings are substantially lower than the temperature of the melt in the furnace. Thermal, physical and chemical inhomogeneities tend to occur in the transport of the glass in the forehearth channels through heat losses at the refractory sides and contact with the sides tending to contaminate the glass with refractory cords. Frequent filament breakouts, formation of nonuniform filaments and other difficulties have been encountered which are believed attributable at least in part to such inhomogeneities in bushings or stream feeders disposed along the forehearth and supplied with glass from the forehearth channel. In stream feeders or bushings conventionally used along a forehearth channel, temperature upsets and inhomogeneities of the glass cannot adequately be correct or abated in a comparatively short time that the glass is resident in the feeder or bushing. To overcome this problem a comparatively deeper bushing or feeder has been used and the glass in the feeder or bushing has been reheated to a temperature approaching but not exceeding the maximum original melt temperature to recondition the glass.
However, the deeper feeders are an expensive answer to the problem. The additional platinum and rhodium alloy required to construct the deeper feeder greatly increases the cost of the feeder. In addition the electrical terminals, that supply electrical energy to the feeder to condition the molten glass, must be larger to properly distribute the energy to the feeder. To construct these larger terminals it is usually necessary to weld a number of pieces together to form the larger terminals. As a result of the need for larger terminals more expensive platinum and rhodium alloy must be used in the terminals. This, of course increases the cost penalty of using a deeper feeder.
Therefore, it is important that an improved electrical terminal be constructed so that relatively shallow feeders can be used to form fibers from molten material. The terminal must be of a design so that the molten material will be given an effective terminal treatment in the short time that the molten material is in the shallow feeder. This type of terminal will greatly reduce the amount of expensive materials used to construct the feeder and will, therefore, improve the cost efficiency of direct melt fiber forming processes.